As for the light-emitting apparatus using a semiconductor light-emitting device, there have been conventionally known, for example, a light-emitting apparatus where as shown in FIG. 1, a light-emitting device is mounted on a lead frame and the entirety is resin-encapsulated in a cannonball shape, and a light-emitting apparatus where as shown in FIG. 2, a reflector is provided on a substrate, a light-emitting device is mounted on the substrate constituting the bottom of a recess formed by the substrate and the reflector, and the inside of the recess or the entire recess is resin-encapsulated. Furthermore, in the light-emitting apparatus shown in FIG. 3, a plurality of light-emitting devices are mounted on a substrate with the intention of mass production, the surface thereof is encapsulated with a sealant or the like, and individual devices are divided by dicing or the like to have a profile of the side surface being nearly perpendicular is known (see, for example, Kokai (Japanese Unexamined Patent Publication) No. 8-78732). In the Figures, 2 indicates a light-emitting device, 4 indicates a substrate, 5 indicates a reflector, 6 indicates a sealant, 7 indicates a mounting-side lead frame, 8 indicates a power supply-side lead frame, 9 indicates a bonding wire, 10 indicates a p-electrode, and 11 indicates an n-electrode. In these light-emitting apparatus, when a material having an intermediate refractive index between the light-emitting device and the air is employed as the encapsulating material, the total reflection inside of the light-emitting device is reduced, but optical self-absorption of the light-emitting device still occurs along the beam trajectory shown by A in the Figures and this gives rise to low light extraction efficiency of almost about 1.2 to 1.5 times the efficiency when encapsulation is not applied.
Furthermore, as for the radiation intensity distribution (or luminous intensity distribution) of light in a light-emitting apparatus using the light-emitting device shown in FIG. 1 or 2, the light is concentrated in one direction mainly by providing a reflector or a lens. In addition, in the configuration of FIG. 3, the main purpose is so that energization of a device can be confirmed by lighting of the light-emitting device, and productivity of the light-emitting apparatus is important, but the light extraction is not improved.
In general, the refractive index of the light-emitting device takes a value of 2.4 to 3.7, and the refractive index of air takes a value of 1.0. A resin having a refractive index of about 1.5 intermediate therebetween is usually used for the encapsulating resin. In order to allow the light emitted from the light-emitting device to go out into air through the encapsulating resin, the angle (θ) between the light incident on the encapsulating resin/air interface and the interface must be larger than the critical angle (θc) represented by the following formula:θc=cos−1(n2/n1)(wherein n1 is the incidence-side refractive index and n2 is the output-side refractive index).
The critical angle (θc) calculated from the refractive index above of the encapsulating resin is about 48°, and if the angle between the interface and the incident light when measured from the interface (reflection surface) to the normal direction of the interface is less than this value, light does not go out of the encapsulating resin. Also, the p-type layer, n-type layer and active layer constituting the light-emitting device generally have a light absorptivity of approximately from 1×10 to 1×104/cm, and therefore particles of light that are multiply-reflected in the encapsulating resin are absorbed by the light-emitting device to inhibit the light extraction.
In the light-emitting device itself, as is known, the light extraction efficiency can be enhanced more than in the conventional nearly rectangular light-emitting device by adjusting the geometric dimension such as the height of the upper clad layer with respect to the active layer and the angle of the side surface of the device (see, for example, U.S. Pat. Nos. 6,229,160, 6,323,063 and 6,570,190). However, in the light-emitting apparatus loaded with a light-emitting device, it is not known to enhance light extraction efficiency by adjusting the geometric dimension.